There are sleeve pin and core pin in sleeve ejector system. Ont the
one hand,we can't put ejector pins in those area,when part have to
be precision tolerance, good dimension, good appearance at holes or
boss.On the other hand,if we do not use sleeve ejector system, most
of the products can been bending, scratch, crack, dimension of hole
of products will not good and difficult for several steps
processing.After read this paragraph you may know the importance of
core pins and sleeves.